1. Technical Field
The present disclosure relates to a switching mode power supply apparatus, and more particularly, to a switching mode power supply apparatus capable of reducing heat generated in a control switch (semiconductor switching element) of an LED control circuit unit.
2. Description of the Related Art
Recently, as a light emitting diode (LED) emerges as a main light source, research into an LED driver is on-going in various fields such as TVs, monitors, and lighting devices. Various types of LED drivers are used depending on applications, and in a case of multiple outputs, a boost converter connected to a main converter in series for current control and dimming is most commonly used. In addition to technology to dominate the market, research into technology to have price competitiveness is also on-going. An LED driver needs not only to regulate current to have a constant value but also to adjust brightness of light by dimming control. In this connection, there has been proposed an approach to eliminate a boost driver to regulate LED current and instead directly regulate current output from a flyback converter commonly used as a main converter, thereby improving price competitiveness of an LED driver. According to this approach, however, a current control switch is frequently turned on and off due to many variations in output voltage from the converter, such that the size of a needed heat dissipation plate becomes larger, as considerable heat is dissipated from the switch, and thus the LED driver becomes less competitive in price.